Functional analysis of the Agrobacterium tumefaciens octopine Ti-plasmid left and right T-region border fragments

Haaren, M. J. J. Van; Pronk, Jack T.; Schilperoort, R. A.; Hooykaas, Paul J. J.

doi:10.1007/bf00016438

Cited by 29 publications

(34 citation statements)

References 43 publications

(34 reference statements)

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“…Wild-type levels of tumorigenesis require the right border repeat and a flanking sequence called overdrive (28,42). Although it plays a nonessential role, the overdrive sequence enhanced T-DNA transmission.…”

Section: Discussionmentioning

confidence: 99%

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Virulence genes, borders, and overdrive generate single-stranded T-DNA molecules from the A6 Ti plasmid of Agrobacterium tumefaciens

1988

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Agrobacterium tumefaciens transfers the T-DNA portion of its Ti plasmid to the nuclear genome of plant cells. Upon cocultivation of A. tumefaciens A348 with regenerating tobacco leaf protoplasts, six distinct single-stranded T-DNA molecules (T strands) were generated in addition to double-stranded T-DNA border cleavages which we have previously reported (K. Veluthambi, R.K. Jayaswal, and S.B. Gelvin, Proc. Natl. Acad. Sci. USA 84:1881-1885, 1987). The T region of an octopine-type Ti plasmid has four border repeats delimiting three T-DNA regions defined as T left (TL), T center (TC), and T right (TR). The six T strands generated upon induction corresponded to the TL, TC, TR, TL + TC, TC + TR, and TL + TC + TR regions, suggesting that the initiation and termination of T-strand synthesis can occur at each of the four borders. Most TL + TC + TR T-strand molecules corresponded to the top T-DNA strand, whereas the other five T strands corresponded to the bottom T-DNA strand. Generation of T strands required the virA, virG, and virD operons. Extra copies of vir genes, harbored on cosmids within derivatives of A. tumefaciens A348, enhanced production of T strands. The presence of right and left border repeats in their native orientation is important for the generation of full-length T strands. When a right border repeat was placed in the opposite orientation, single-stranded T-DNA molecules that corresponded to the top strand were generated. Deletion of overdrive, a sequence that flanks right border repeats and functions as a T-DNA transmission enhancer, reduced the level of T-strand generation. Induction of A. tumefaciens cells by regenerating tobacco protoplasts increased the copy number of the Ti plasmid relative to the bacterial chromosome.

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Section: Discussionmentioning

confidence: 99%

“…The T-DNA borders are cis-acting components that functionally define the T-DNA region. The rightward border repeat is required in its native orientation together with its flanking sequences (overdrive) for efficient transformation of plant cells (14,15,28,29,42,44).…”

mentioning

confidence: 99%

Virulence genes, borders, and overdrive generate single-stranded T-DNA molecules from the A6 Ti plasmid of Agrobacterium tumefaciens

1988

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“…This enhancer has been found to be specifically recognized by VirC1 protein (Toro et al, 1989). Deletion of virC operon is followed by attenuation of virulence of the Agrobacterium strains (van Haaren at al., 1987;Rogowsky et al, 1990). …”

Section: Generation Of T-dna Transfer Complexmentioning

confidence: 99%

Agrobacterium tumefaciens: a natural tool for plant transformation

Riva¹,

Gonzalez-Cabrera²,

Vázquez-Padrón³

et al. 1998

Electron. J. Biotechnol.

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Updated information of mechanisms for T-DNA transfer to plant cells by Agrobacterium tumefaciens is provided, focused on the role played by the different components of the virulence system. The general assessments for the establishment of efficient transformation protocols are discussed with an emphasis in the application of this methodology to monocotyledonous plants. Based on our own experience, we present the establishment of sugarcane transformation by A. tumefaciens as a model of application of this methodology to an important culture plant specie, previously considered recalcitrant and inaccessible for this type of genetic manipulation.

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“…This is not the only reason for the difference in activity though. For the octopine Ti plasmid it has been shown that an extra sequence is present next to the right border repeats (but not near left border repeats) which stimulates the transfer process [19,23]. This T region transfer enhancer has been called overdrive [19].…”

Section: Successful Transformation Of Plant Cells Bymentioning

confidence: 99%

“…For cloning purposes the vectors plC19R and plC20R and the shuttle vector pRAL5200 were used [13,23]. A synthetic right border fragment (SRB) of the octopine pTi15955 TL region and the synthetic right border of the nopaline pTiT37 plasmid T region were inserted in plC19R as Sal 1-Hind III fragments.…”

Section: Construction Of Plasmidsmentioning

confidence: 99%

Function of heterologous and pseudo border repeats in T region transfer via the octopine virulence system of Agrobacterium tumefaciens

et al. 1988

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The successful transfer of the Ti plasmid T region to the plant cell is mediated by its 24 bp border repeats. Processing of the T-region prior to transfer to the plant cell is started at the right border repeat and is stimulated by a transfer enhancer sequence called "overdrive". Left and right border repeats differ somewhat in nucleotide sequence; moreover, the repeats of different Ti and Ri plasmids are slightly different. Our data indicate that these differences do not have a significant influence on border activity. However, the overdrive sequence is essential for the efficient transfer of a T region via an octopine transfer system. Our data suggest that an overdrive sequence must also be present next to the right border repeats of the nopaline Ti plasmid and the agropine of octopine and nopaline Ti plasmids express some differences in T-DNA processing activities. of cotopine and nopaline Ti plasmids express some differences in T-DNA processing activities.Furthermore, we demonstrate that certain pseudo border repeats, sequences that resemble the native 24 bp border repeat and naturally occur within the octopine Ti plasmid T-region, are able to mediate T region transfer to the plant cell, albeit with much reduced efficiency as compared to wild-type border repeats.

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Functional analysis of the Agrobacterium tumefaciens octopine Ti-plasmid left and right T-region border fragments

Cited by 29 publications

References 43 publications

Virulence genes, borders, and overdrive generate single-stranded T-DNA molecules from the A6 Ti plasmid of Agrobacterium tumefaciens

Virulence genes, borders, and overdrive generate single-stranded T-DNA molecules from the A6 Ti plasmid of Agrobacterium tumefaciens

Agrobacterium tumefaciens: a natural tool for plant transformation

Function of heterologous and pseudo border repeats in T region transfer via the octopine virulence system of Agrobacterium tumefaciens

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